One of their main attractions, says Mayor Brainard, is safety. The Insurance Institute for Highway Safety, an independent research group, estimates that converting intersections with traffic lights to roundabouts reduces all crashes by 37% and crashes that involve an injury by 75%. At traffic lights the most common accidents are faster, right-angled collisions. These crashes are eliminated with roundabouts because vehicles travel more slowly and in the same direction. The most common accident is a sideswipe, generally no more than a cosmetic annoyance.

What locals like, though, is that it is on average far quicker to traverse a series of roundabouts than a similar number of stop lights. Indeed, one national study of ten intersections that could have been turned into roundabouts found that vehicle delays would have been reduced by 62-74% (nationally saving 325,000 hours of motorists’ time annually). Moreover, because fewer vehicles had to wait for traffic lights, 235,000 gallons of fuel could have been saved.

I’ve never cycled in a proper large one, but I have driven in them. They beat sitting at a red light, but are slower than a green light. However, their efficiency comes from the fact you don’t have to sit there (like you do a red light) even when there is no competing traffic.

The small ones they put in residential areas I dislike more than the stop signs they replace. People go flying into them without following correct procedures.

As a cyclist, I do not like large roundabouts. Perhaps a factor is that I do not see that many . The cars are intent on continuing to move. If you intend as a cylcist to go straight or turn left , you will be crossing the traffic flow on one and two occasions respectively. The last large roundabouts I rememeber as a cylist was in Cuba and Mexico. I did not enjoy them and felt more vulnerable.

The small roundabouts that I see around Vancouver are designed for slowing traffic. Those are fine.

Small roundabouts are fine – better for bikes than stop signs, because you don’t lose momentum as much. As a cyclist in the UK I found large roundabouts pretty frightening, because of the need to change lanes through constant, busy, constantly-switching-lanes car traffic that moves much faster than you. Cars coming off multiple-lane roads with 60mph limits often still drive quickly through roundabouts, definitely fast enough to kill any cyclist they hit, they’re not looking for cyclists and thus liable to hit you, and it can leave cyclists with the feeling of dodging bullets. I’m a confident, competent cyclist (and in fact I’ve cycled safely around Hype Park Corner, although it was a bit nerve-wracking), but there are journeys in the UK I simply wouldn’t make by bike solely because they involve crossing busy roundabouts that feed into and out of multi-lane roads with 60 mph limits that the motorists treat effectively as motorways. The only way I can see to make big roundabouts feel safe for cyclists is to impose a very low speed limit – close to or at cycling speed, certainly no more than 25mph – and enforce the living hell out of it with near-constant policing and massive fines. But since that will never happen, the big roundabouts are a real problem, and IMHO much sketchier and more deterrent for cyclists than a traffic light would be in that location.

I cycled along a “bicycle lane” on a main arterial connector (Marine Drive) in North Vancouver today. It was rush hour and the cares were completely backed up. On average three or four cars per car, a stopped car was in the “bike lane”. I was disappointed but not surprised.

I look forward to when there is such a critical mass of cyclists that bicycle routes are seperated or at least much safer.

I think the conflict is decieving – what’s best for cars is for there to be fewer cars around, so an infrastructure less car friendly could actually produce better results for drivers. I don’t think designing a more bike friendly city is difficult from a technical point of view; it’s difficult from a political point of view because we have a reactionary and unsophisticated political discourse.